The Colossus was indeed a spectacular achievement and a major force in winning the war in Europe.
However, it was not a Turing-complete machine because it lacked a conditional goto capability. Basically, it was a high-speed comparator where the Boolean comparisons could be programmed.
The first Turing-complete computer was built by a German, Konrad Zuse.
Eniac was the first computer to be expressly built to be Turing-complete.
If you want to highlight the contribution of England to the development of the modern computer, look into the postwar work done at Manchester University.
Like most of the highly complex technical developments of the twentieth century, it's almost impossible to attribute the development of the computer to a single country, much less a single individual.